HAVANA -- Fidel Castro lashes out against U.S. biofuel plans in an op-ed piece published Thursday, a sign Cuba's 80-year-old leader may be taking a more active role in public affairs after months sidelined by a still undisclosed illness.

The article is written in the same kind of apocalyptic style Castro typically adopts when discussing the impact of U.S. international policies on developing nations, and there was no reason to doubt he was the author.

President Bush's support for using crops to produce ethanol for cars could deplete food stocks in developing nations, the article in the Communist Party daily Granma asserts.

The headline reads: "Condemned to Premature Death by Hunger and Thirst more than 3 Billion People of the World."

"This isn't an exaggerated number; it is actually cautious," says the article distributed by e-mail early Thursday to international correspondents by foreign ministry officials.

As in some shorter messages signed by Castro in the eight months since he fell ill, the piece does not seem aimed at dispelling rumors about his health, but rather at drawing attention to his stand on world affairs.

It was unclear what the message means in terms of Castro's future role in domestic affairs.

In recent weeks, Bolivian President Evo Morales and several senior Cuban officials have indicated that Castro could soon take a more active role in public affairs and may even return to the presidency.

Castro temporarily ceded power to his younger brother Raul, the 75-year-old defense minister, on July 31 after announcing he had undergone intestinal surgery. He has not appeared in public since.

Morales recently said from Bolivia that he expects to see Castro in public on April 28 during a meeting in Havana with presidents celebrating a regional trade and cooperation pact.

Castro's condition and his exact ailment are a state secret but he is widely believed to suffer from diverticular disease, which causes a weakening in the walls of the colon.

His older brother Ramon Castro told reporters Wednesday that Fidel was doing very well but dodged questions about whether he would soon appear in public. "He's in one piece," Ramon Castro, 82, said of Fidel as he toured a cattlemen's fair and rodeo. "These Castros are strong!"

In his Thursday article, Fidel Castro quotes extensively from a Washington-datelined story by The Associated Press reporting on a meeting Monday between Bush and U.S. automakers and their comments about using corn to create ethanol as an alternative to fossil fuels.

"The sinister idea of converting food into combustible was definitively established as the economic line of the foreign policy of the United States," he writes.

The Cuban leader notes that Cuba has also experimented with extracting ethanol from sugarcane.

But if rich nations decide to import huge amounts of traditional food crops such as corn from developing countries to help meet their energy needs, it could have disastrous consequences for the world's poor, Castro writes.

"Apply this recipe to the countries of the Third World and you will see how many people among the hungry masses of our planet will no longer consume corn," the article said. "Or even worse: by offering financing to poor countries to produce ethanol from corn or any other kind of food no tree will be left to defend humanity from climate change."